In the micro-technology field, especially the field of microelectronics, power electronics, optoelectronics and MEMS-type components, it is known to use composite substrate structures comprising silicon wafers bonded to an insulating layer of the SOI type
Methods for fabricating such composite structures are known in the art. Certain known methods form an insulating layer internal to a substrate by implanting oxygen species through the face the substrate. Certain other known methods split or cleave a thin semiconductor layer from a donor substrate at a zone of weakness within the donor substrate and then transfer the thin layer onto a support substrate having a surface insulating layer.
Different techniques for forming such zones of weakness are known in the art. In one such technique, the zone of weakness is formed within the donor substrate by the implantation of atomic species through the face of the donor substrate. In another such technique, the zone of weakness is a porous layer within the donor substrate. This porous layer is formed by, first, performing a wet electrochemical process to make the surface of a substrate porous, and then by depositing the layer to be transferred onto the porous surface.
However, these known methods have various disadvantages. Those methods that require implantation can damage the crystal structure of material being implanted. Those methods that require forming a porous layer by electrochemical means necessarily require immersion in a solution which can lead to contamination.